JPH0944857A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a stable focus setting by providing a means to avoid an influence when a groove-mixed signal level is detected and its level is high. SOLUTION: A pickup 12 includes an objective lens 5 casting a light beam onto an optical disk 2, a focus error detection unit 11 detects a focus error signal from the reflected light obtained from the reflection of the light beam on the recording surface on the optical disk 2. A focus pull-in means is functionally constituted of a CPU 1, a servo control circuit 10, the focus error detection unit 11, etc., and detects that the objective lens has focalized around on the recording surface of the optical disk 2 from the focus error signal Se. The groove-mixed detection device 14 detects the groove-mixed signal level mixed into the focus error signal Se and a spindle driving circuit 4 halts the rotation of the optical disk 2 when the groove-mixed signal level is at a level to cause a malfunction of the focus pull-in means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc device for reading information recorded on a disc.

[0002]

2. Description of the Related Art In recent years, in a disk device that reads information recorded on an optical disk such as a CD (compact disk) and an optical magnetic disk such as an MD (mini disk), a light beam is irradiated onto a track on the recording surface of the disk by a pickup. Then, the recorded information is reproduced by receiving the reflected light beam. The light beam emitted from the laser light source of the pickup is converged by the objective lens and applied to the disc. In this case, a focus servo that keeps the focus of the light beam on the recording surface of the disc and a tracking servo that keeps the light beam at the center of the track of the disc are performed. When pulling in the focus servo so that the light beam focuses on the recording surface of the disc, the objective lens is driven by the focus actuator and the pickup including the objective lens is moved toward or away from the disc. The reflected light from the recording surface of the objective lens is received, and a focus error signal is generated by, for example, an astigmatism method, a knife edge method, or a Foucault method. Is detected to be passing near the in-focus position, and the focus servo is closed to perform focus pull-in. In the conventional disk device, the focus servo for holding the focus of the light beam on the recording surface of the disk is usually drawn in this way.

[0003]

However, in the above-mentioned conventional disk device, when the optical component of the pickup is displaced or the shape of the light beam of the laser light source is distorted, the light beam is emitted from the disk. While passing through the track, the focus error signal is affected by the shape of the groove forming the track, and the groove mixing signal is superimposed on the focus error signal. The detection method (generally the astigmatism method is easily affected by passing tracks) and the groove shape of the track will cause a large change, and if the level of this groove mixing signal is large, the focus error signal at the time of focus pull-in will occur. There was a problem that the focus could not be correctly detected due to the disturbance and focus pull-in failed.

The present invention solves the above-mentioned problems by providing a means for detecting the level of a groove-mixed signal and avoiding its influence when the level is high.
An object of the present invention is to provide a disk device that realizes stable focus pull-in.

[0005]

To achieve the above object, the present invention provides a first means: a disk device for irradiating a recording area of a rotating optical disk with a light beam to read recorded information. A pickup including an objective lens that irradiates the optical disc with the light beam; and a focus error signal detection unit that detects a focus error signal from reflected light obtained by reflecting the light beam on a recording surface of the optical disc. A focus pull-in unit that detects that the objective lens has focused on the recording surface of the optical disc from the focus error signal and performs focus pull-in is provided.

Second means: A disk device for irradiating a recording area of a rotating optical disk with a light beam to read recorded information, the pickup including an objective lens for irradiating the optical disk with the light beam; Light beam moving means for moving the light beam over the entire recording area of the optical disk, area identifying means for identifying an irradiation position of the light beam, and the light beam reflected by a recording surface on the disk Focus error signal detection means for detecting a focus error signal from the reflected light obtained by, groove mixing detection means for detecting the signal level of the groove mixing signal mixed in the focus error signal, and the objective lens from the focus error signal When the focus on the recording surface of the optical disc is detected, focus pull-in is performed. A focus beam pulling means is provided, and the signal level of the groove mixing signal obtained from the recording area of the optical disc is recognized by the area identifying means as a light beam irradiation position within a signal level range in which the focus pulling means operates normally, The focus is pulled in at that position.

[0007]

According to the above-described structure of the present invention, stable focus pull-in can be performed by monitoring the level of the groove-mixed signal and performing focus pull-in while avoiding an excessive amount of mixed groove. .

[0008]

Embodiments of the present invention will be described below with reference to FIGS.
Will be described with reference to. FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a disk device of the present invention, and FIG. 2 is an explanatory diagram regarding a groove mixing signal which is a problem at the time of focus pull-in in this embodiment. In FIG. 1, 1 is a CPU as a control means for the entire disc device, 2 is an optical disc on which information such as music is recorded, and 3 is a spindle motor which is a rotation driving means for the optical disc 2, and an output of a spindle drive circuit 4. Further, the spindle drive circuit 4 drives the spindle rotation instruction signal S from the CPU 1.
The rotation / stop of the spindle motor 3 is controlled by d. Reference numeral 5 denotes an objective lens that converges and irradiates the optical beam 2 emitted from the laser light source 6 onto the optical disc 2. The objective lens 5 can be moved mainly by its spring means, not shown, in the optical axis direction or in the direction perpendicular to the optical axis to change its posture. It is supported as described above, and is further provided with a magnet as its moving means. 8
Is an actuator, a focusing drive coil,
It consists of a tracking drive coil and a yoke, and the attitude of the objective lens is changed by the electromagnetic force due to the interlinkage with the magnet according to the drive current supplied to these coils, and the focus search, focus servo, and tracking are performed by this change in the attitude. Servo is made.

Reference numeral 9 is an actuator drive circuit as an actuator drive means for supplying a drive current to the actuator 8, 10 is a servo control circuit as a servo control means for giving a drive instruction signal to the actuator drive circuit 9, 11
Is a focus error detection unit that receives the reflected light from the optical disc 2 and outputs a detection signal Sf for generating a focus error signal Se by the astigmatism method. The focus error detection unit is a pickup 12 together with the objective lens 5, the laser light source 6, and the actuator 8. Are configured. Reference numeral 13 denotes a focus error amplifier that outputs a focus error signal Se from the detection signal Sf, which constitutes a focus error signal detection means together with the focus error detection unit 11. Reference numeral 14 is a groove mixing detector for detecting the level of the groove mixing signal mixed in the focus error signal Se when the light beam 7 focused on the optical disk 2 passes the track of the optical disk 2, and 15 is a moving means of the light beam 7. With a DC motor, this DC motor 15
The pickup 12 is moved in the radial direction of the optical disk 2 by rotationally driving. A DC motor drive circuit 16 supplies a drive current to the DC motor 15 and is controlled by a movement instruction signal Sm from the CPU 1. Reference numeral 17 is a pickup position detection switch which serves as an area identification means.
It is turned on when 12 is in a specific area of the optical disc 2.

Next, the operation will be described. The focus pull-in, which is the main object of the present invention, is first performed by the servo control circuit 1 by the focus search signal Ss output from the CPU 1.
By giving an instruction to 0, the actuator drive circuit 9
Drives the actuator 8 to move the objective lens 5 closer to or farther from the optical disc 2, and the focus error amplifier 13 outputs a focus error signal Se. By monitoring the focus error signal Se by the CPU 1, it is detected that the objective lens 5 is near the focus position, and the CPU 1 outputs the focus on signal Sn to the servo control circuit 10 to close the focus servo loop. Instruct and focus pull-in is completed. The groove mixing signal, which is a problem at this time, is shown in FIG.
It becomes as shown in.

That is, FIG. 2A shows a state in which the light beam 7 converged by the objective lens 5 is focused on the track on the optical disk 2, and the light beam spot is distorted by the track. I understand. Due to this distortion, the light beam 7 is diffracted, but depending on the shape of the emission beam of the laser light source 6, the assembly accuracy of the optical element incorporated in the pickup 12 and the groove shape of the track on the optical disk 2, the light beam spot may be a track. When passing over, Figure 2
As shown in (b), the groove mixing signal is superimposed on the focus error signal Se. FIG. 2C shows a focus error signal Se in the vicinity of the focus position when the objective lens 5 is moved away from the optical disc 2 by outputting the focus search signal Ss from the CPU 1.
Shows the movement of the case where there is no groove mixing signal and the case where the level of the groove mixing signal is high.

In FIG. 2 (c), when there is no groove mixing signal, the CPU 1 can correctly detect the focus position by monitoring the focus error signal Se. When this is detected, the CPU 1 causes the servo control circuit 10 to detect. On the other hand, the focus-on signal Sn is output, and the focus pull-in can be achieved. However, when the level of the groove mixing signal is high, the focus error signal Se is disturbed as shown in the figure,
The CPU 1 that monitors the focus error signal Se cannot correctly detect the focus position and outputs the focus-on signal Sn at a position other than the focus position, resulting in failure in focus pull-in.

The present invention pays attention to this point, and as a first means for solving the problem, as a first means for solving the problem, the level of the groove mixing signal which causes the focus pull-in failure is detected by the groove mixing detecting device 14, and the groove mixing signal is detected. When the level is a level at which focus pull-in may fail, the CPU 1 is informed of that fact, and the CPU 1 which received the notice stops the spindle motor 3 so that the groove mixing signal is not mixed and the focus is adjusted. It is designed to be retracted. In this case, since the optical disc 2 is rotated after the focus pull-in is performed, the disc device requires some rise time, but the result is far better than the situation in which the focus pull-in fails. When the level of the groove-mixed signal is a signal level that does not affect the focus pull-in, it is not necessary to stop the spindle motor 3, and the focus pull-in can be performed in the rotated state. You can shorten the waiting time before playing.

The second means is that when the recording area is divided into a plurality of parts as the structure of the optical disk 2 and each groove has a different groove-shaped track, the level of the groove mixing signal differs depending on the recording area. The DC motor 15 for moving the light beam is rotationally driven to move (scan) the light beam over the entire recording area of the optical disc 2, and the CPU controls the area where the level of the groove mixing signal is the lowest.
1 and pickup position detection switch as area identification means
After being recognized by 17, the pickup 12 is moved to this area to perform focus pull-in at this position, and stable focus pull-in can be performed while the optical disc 2 is rotated. In this case as well, the waiting time until the information is reproduced from the optical disk 2 can be shortened as in the above case.

In this way, the level of the groove mixing signal which causes the failure of the focus pull-in is detected, and whether the focus pull-in is possible or not is judged based on the level, and the rotation of the optical disk is stopped or the focus pull-in is continued with the optical disc being rotated. It is possible to perform stable focus pull-in.

[0016]

As described above, according to the present invention, the level of the groove mixing signal is monitored, and the focus pull-in is performed while avoiding the excessive mixing amount, so that the pull-in does not fail. A stable focus pull-in is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a disk device of the present invention.

FIG. 2 is an explanatory diagram regarding a groove mixing signal in the embodiment of the disk device of the present invention.

[Explanation of symbols]

1 ... CPU, 2 ... Optical disk, 3 ... Spindle motor, 4 ... Spindle drive circuit, 5 ... Objective lens,
6 ... Laser light source, 7 ... Light beam, 8 ... Actuator, 9 ... Actuator drive circuit, 10 ... Servo control circuit, 11 ... Focus error detection unit, 12 ... Pickup, 13 ... Focus error amplifier, 14 ... Groove mixture detection device, 15 ... DC motor, 16 ... DC motor drive circuit, 17 ... Pickup position detection switch.

Claims (3)

[Claims] 1. A disc device for irradiating a recording area of a rotating optical disc with a light beam to read recorded information, the pickup including an objective lens for irradiating the optical disc with the light beam, and the light beam. Focus error signal detecting means for detecting a focus error signal from reflected light obtained by reflecting on the recording surface of the optical disc; and that the objective lens focuses on the recording surface of the optical disc from the focus error signal. And a groove mixing detection unit that detects a signal level of a groove mixing signal mixed in the focus error signal, and a signal level of the groove mixing signal causes malfunction of the focus drawing unit. Rotation that stops the rotation of the optical disc when it is at a level that invites A disk device including control means. 2. The disk device according to claim 1, wherein the focus error signal detecting means uses an astigmatism method. 3. A disk device for irradiating a recording area of a rotating optical disk with a light beam to read recorded information, the pickup including an objective lens for irradiating the optical disk with the light beam; Light beam moving means for moving the light beam over the entire recording area, area identifying means for identifying the irradiation position of the light beam, and the light beam reflected by the recording surface on the disk Focus error signal detecting means for detecting a focus error signal from reflected light, groove mixing detecting means for detecting a signal level of a groove mixing signal mixed in the focus error signal, and the objective lens on the optical disk from the focus error signal When the focus on the recording surface is detected, the focus pull-in is performed. The area identifying means recognizes a light beam irradiation position where the signal level of the groove-mixed signal obtained from the recording area of the optical disk is within a signal level range in which the focus drawing means operates normally. A disk device characterized by performing focus pull-in at a position.